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Hey all,
I know this is a topic that has been discussed A LOT but I haven't found much with exact intentions. I have a 2013 automatic. With the 3.6L it seems my MPG is rather low given my mods. I have 35" mts and a 2" lift. My mpg are about 13-13.5 with a 50/50 split of highway/city driving. I am looking into regearing to 4:56s gears and my question is will I see an increase in mpg or.am I better off regearing to 488s. Any help and feedback is appreciated!
 

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How do you use your rig? Do you wheel often and do you plan on going to 37's anytime in the near or distant future?
 

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It seems like your getting pretty crappy mileage for sure. I'm not so sure your mileage will improve that much though. May want to have the dealer check things out to see if there are other problems going on. Drives me nuts how these motors vary so much in mpg's. 4.88's would be my minimum and even then you could find yourself wishing for 5.13's.

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I would not do 4.88 with 35's. I am running 4.88 with 38's and it runs 2700rpm at 70mph. When I ran 37's it could go either way 4.56 or 4.88. If you run 35's go 4.56 and if later you decide to go bigger they will work with 37's as well. This is on my 2012 auto JKU.
 

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I would not do 4.88 with 35's. I am running 4.88 with 38's and it runs 2700rpm at 70mph. When I ran 37's it could go either way 4.56 or 4.88. If you run 35's go 4.56 and if later you decide to go bigger they will work with 37's as well. This is on my 2012 auto JKU.
Holy crap, that much diff on the 3.6 eh? How well do you hook up to od on steep inclines and hills at hwy speeds?
 

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Depends on the incline.
Yeah that's always my concern with not going a little taller. Have to compromise some between auto and stick...
 

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I very rarely drops lower then 4th unless the incline is steep on the highway.
So your stick, not auto. Pretty big difference. Stick I say 4.56-4.88 works well depending on your terrain and which t-case your running. Auto, not so much unless just around town. Also, I don't shoot for running down the freeway at 70-80mph either butI know many do on their daily commutes.
 

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I have a 2012 JKU w/3.6 & auto and live down here in the flatlands in Florida. I have a RK 2.5" Max Travel Pro lift, 35x12.5x17 tires, Steel bumpers, winch on the front, etc., and the shop that did the work suggested and installed 4:88 gears w/my 35's. I can say that with 4:88 gears and 35's, that they are geared a little bit much for the flatland but if you ever go to 37's the 4:88's will be perfect. I went to the Smokey Mountains for vacation and the 4:88 gearing and 35's pushed the Jeep through whatever I drove it through with ease and I think it would still perform very well in the mountains with 37's.
With that said, if you are just a weekend warrior and you are not in the big hills, get the 4:56 gears. If you are wanting to do some more difficult off-road adventures or think you may be wanting 37's in the future, get the 4:88 gears.
Also I am getting about 14 to 15.5 MPG with 4:88 gears.
 

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So your stick, not auto. Pretty big difference. Stick I say 4.56-4.88 works well depending on your terrain and which t-case your running. Auto, not so much unless just around town. Also, I don't shoot for running down the freeway at 70-80mph either butI know many do on their daily commutes.
If you check back on post #5 I included I'm an auto.
 
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